Angular and linear spinal parameters associated with relaxed and erect postures in healthy subjects

Area of Science:

• Biomechanics
• Orthopedics
• Human Posture Analysis

Background:

• Accurate spinal posture assessment is crucial for physical evaluations and detecting changes.
• Reproducible measurement of spinal curves is necessary for reliable postural monitoring.

Purpose of the Study:

• To assess the reproducibility of cervical, thoracic, and lumbar spinal curves in healthy young adults.
• To investigate changes in spinal curves and stature when transitioning from relaxed to erect standing.

Main Methods:

• An ultrasound-based system was used to measure spinal curves (cervical, thoracic, lumbar) in 30 subjects twice over a week.
• 28 subjects underwent single measurement sessions to record curves in relaxed and erect postures, plus stature via stadiometer.
• Reproducibility was analyzed using interclass correlation coefficients (ICC), standard error of measurement (SEM), and smallest real difference (SRD).

Main Results:

• Excellent reproducibility was found for thoracic curves (ICC=0.95), good for lumbar (ICC=0.85), and poor for cervical (ICC=0.68).
• Transitioning to erect posture caused significant thoracic angle changes (7.2° in men, 4.8° in women) and height increases (1.3 cm men, 0.8 cm women).
• These postural changes were more pronounced in men, with significant correlation between angular and height differences.

Conclusions:

• Ultrasound-based spinal curve measurements demonstrate high reproducibility for thoracic curvature in young healthy adults.
• The smallest real difference (SRD) for thoracic curves can serve as a criterion for assessing postural flexibility.
• Erect posture significantly alters spinal alignment and stature, with notable sex-based differences in response.